FMC Problem

[Guest]

Hey people! When I load my 767 PIC and try to open the FMS to initialize my route, I see the FMS with the

[Guest]

Clear the message and enter your IRS Position on the POS page.

[Guest captbulldog]

yea that'll do

[Guest TheJones]

This message means you have to tell the FMC exactly where the plane is. The message appears whenever the IRS have not finished aligning - if IRS are aligned, the (average of three) coordinates will be transfered to the FMC and no further action is needed.If you want to manually enter coordinates, you can do so and the coordinates will transfer from the FMC to the IRS during alignment.A sidenote: Whenever you get a message in the FMC's scratchpad, it will "block" any data entry and you have to clear it. You will also get the advisory "FMC message" and a white announciator light ("FMC").Finally, do yourself a big favour and read the manual. twice actualy. Page 10 in FMC manual explains exactly the set position flow.Hope I helped,Ilan

[Guest Ian_Riddell]

"The message appears whenever the IRS have not finished aligning -"Interesting point... I've noticed that a 747-400 only puts up the message after the full 10 minute alignment period has elapsed (and no pos entry has been made). On the 767's I've last tried it on, the ENTER IRS POSITION msg seems to appear after 3 or 4 minutes (well before the 10 minute mark)." if IRS are aligned, the (average of three) coordinates will be transfered to the FMC and no further action is needed."Actually, no averages are sent to the FMC. The FMC does the averaging from IRS raw data (which, in this case, should be the single pos entry you sent to the 3 IRS's).I'd be interested to know what would happen to the CDU & EHSI displays on aircraft fitted with GPS if a slightly incorrect IRS position was entered into the POS INIT boxes. Would the map shift to the IRS position, then slowly slew back to the correct GPS position, or would the IRS entry be ignored and the Map remain in the GPS position?Cheers.Ian.